The term “battery” is used herein to include accumulators. In a conventional lead-acid battery it is customary to connect together the plates of each stack by means of a lead strap or post which is fixed to aligned lugs or tabs on the plates.
In the manufacture of batteries, particularly for example lead acid batteries, it is known to cast battery components. Components such as straps and other formations can also be simultaneously cast onto the lugs of battery plates so as to, for example, form a connection between a set of plates within a cell of the battery. Such straps are generally cast by filling a mould cavity with lead and dipping lugs into the cavity prior to the cooling of the lead. Typically, the mould cavities are filled by allowing lead to flow into channels at the sides of the cavities and spill over a weir into the mould.
An example of a typical casting apparatus is shown in the Applicant's earlier application WO94/16466 in which the apparatus includes a mould having a set of post or strap mould cavities, a molten metal feed duct adjacent thereto, a weir between the feed duct and the cavities, means for supplying molten lead to the duct, and hence the cavities, a pump and at least a pair of substantially parallel feed passages extending below the duct and connected to the duct.
It is important that the flow of lead into all of the mould cavities is carefully controlled during the casting of components. Ideally the flow of molten lead should be balanced or controlled along the length of the mould trough so that all the cavities fill at the same time and at the same rate. Such balancing of the flow is difficult to achieve with existing apparatuses and may for example be effected by manufacturing tolerances and operating conditions in the mould and/or supply.
A further complication arises, when left and right sets of mould cavities are provided, each having an adjacent feed duct and associated feed passages. In this case it desirable that the flow of molten lead is balanced between the left and right sides.
The applicant has previously attempted to address the problem of left and right side flow control (or left and right flow balancing) by providing a throttle bolt in either the left or the right feed passage at the pump end. The throttle bolt can be adjusted to alter the flow rate of the molten metal through the passage to ensure that the left and right mould cavities are filled at an even rate.
A further possible solution to the problem of balancing the flow of molten metal is to provide multiple supply pumps and inlets, and to regulate each individually. However, this increases the complexity and cost of the apparatus.
Embodiments of the invention seek to provide an apparatus which may provide improved delivery of lead to the mould cavities.